linux-toradex.git/include/uapi/linux/mman.h, branch v6.4-rc1

powerpc/8xx: Support 16k hugepages with 4k pages

2020-09-15T12:13:31+00:00

The 8xx has 4 page sizes: 4k, 16k, 512k and 8M

4k and 16k can be selected at build time as standard page sizes,
and 512k and 8M are hugepages.

When 4k standard pages are selected, 16k pages are not available.

Allow 16k pages as hugepages when 4k pages are used.

To allow that, implement arch_make_huge_pte() which receives
the necessary arguments to allow setting the PTE in accordance
with the page size:
- 512 k pages must have _PAGE_HUGE and _PAGE_SPS. They are set
by pte_mkhuge(). arch_make_huge_pte() does nothing.
- 16 k pages must have only _PAGE_SPS. arch_make_huge_pte() clears
_PAGE_HUGE.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/a518abc29266a708dfbccc8fce9ae6694fe4c2c6.1598862623.git.christophe.leroy@csgroup.eu

mm/mremap: add MREMAP_DONTUNMAP to mremap()

2020-04-02T16:35:30+00:00

When remapping an anonymous, private mapping, if MREMAP_DONTUNMAP is set,
the source mapping will not be removed.  The remap operation will be
performed as it would have been normally by moving over the page tables to
the new mapping.  The old vma will have any locked flags cleared, have no
pagetables, and any userfaultfds that were watching that range will
continue watching it.

For a mapping that is shared or not anonymous, MREMAP_DONTUNMAP will cause
the mremap() call to fail.  Because MREMAP_DONTUNMAP always results in
moving a VMA you MUST use the MREMAP_MAYMOVE flag, it's not possible to
resize a VMA while also moving with MREMAP_DONTUNMAP so old_len must
always be equal to the new_len otherwise it will return -EINVAL.

We hope to use this in Chrome OS where with userfaultfd we could write an
anonymous mapping to disk without having to STOP the process or worry
about VMA permission changes.

This feature also has a use case in Android, Lokesh Gidra has said that
"As part of using userfaultfd for GC, We'll have to move the physical
pages of the java heap to a separate location.  For this purpose mremap
will be used.  Without the MREMAP_DONTUNMAP flag, when I mremap the java
heap, its virtual mapping will be removed as well.  Therefore, we'll
require performing mmap immediately after.  This is not only time
consuming but also opens a time window where a native thread may call mmap
and reserve the java heap's address range for its own usage.  This flag
solves the problem."

[bgeffon@google.com: v6]
  Link: http://lkml.kernel.org/r/20200218173221.237674-1-bgeffon@google.com
[bgeffon@google.com: v7]
  Link: http://lkml.kernel.org/r/20200221174248.244748-1-bgeffon@google.com
Signed-off-by: Brian Geffon 
Signed-off-by: Andrew Morton 
Tested-by: Lokesh Gidra 
Reviewed-by: Minchan Kim 
Acked-by: Kirill A. Shutemov 
Acked-by: Vlastimil Babka 
Cc: "Michael S . Tsirkin" 
Cc: Arnd Bergmann 
Cc: Andy Lutomirski 
Cc: Will Deacon 
Cc: Andrea Arcangeli 
Cc: Sonny Rao 
Cc: Minchan Kim 
Cc: Joel Fernandes 
Cc: Yu Zhao 
Cc: Jesse Barnes 
Cc: Nathan Chancellor 
Cc: Florian Weimer 
Link: http://lkml.kernel.org/r/20200207201856.46070-1-bgeffon@google.com
Signed-off-by: Linus Torvalds

arch: move common mmap flags to linux/mman.h

2019-02-18T16:49:30+00:00

Now that we have 3 mmap flags shared by all architectures,
let's move them into the common header.

This will help discourage future architectures from duplicating code.

Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Arnd Bergmann

mm/hugetlb: add mmap() encodings for 32MB and 512MB page sizes

2018-10-05T23:32:04+00:00

ARM64 architecture also supports 32MB and 512MB HugeTLB page sizes.  This
just adds mmap() system call argument encoding for them.

Link: http://lkml.kernel.org/r/1537841300-6979-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual 
Acked-by: Punit Agrawal 
Acked-by: Mike Kravetz 
Cc: Michal Hocko 
Cc: Will Deacon 
Cc: Catalin Marinas 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

License cleanup: add SPDX license identifier to uapi header files with no license

2017-11-02T10:19:54+00:00

Many user space API headers are missing licensing information, which
makes it hard for compliance tools to determine the correct license.

By default are files without license information under the default
license of the kernel, which is GPLV2.  Marking them GPLV2 would exclude
them from being included in non GPLV2 code, which is obviously not
intended. The user space API headers fall under the syscall exception
which is in the kernels COPYING file:

   NOTE! This copyright does *not* cover user programs that use kernel
   services by normal system calls - this is merely considered normal use
   of the kernel, and does *not* fall under the heading of "derived work".

otherwise syscall usage would not be possible.

Update the files which contain no license information with an SPDX
license identifier.  The chosen identifier is 'GPL-2.0 WITH
Linux-syscall-note' which is the officially assigned identifier for the
Linux syscall exception.  SPDX license identifiers are a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.  See the previous patch in this series for the
methodology of how this patch was researched.

Reviewed-by: Kate Stewart 
Reviewed-by: Philippe Ombredanne 
Reviewed-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

mm: arch: consolidate mmap hugetlb size encodings

2017-09-07T00:27:28+00:00

A non-default huge page size can be encoded in the flags argument of the
mmap system call.  The definitions for these encodings are in arch
specific header files.  However, all architectures use the same values.

Consolidate all the definitions in the primary user header file
(uapi/linux/mman.h).  Include definitions for all known huge page sizes.
Use the generic encoding definitions in hugetlb_encode.h as the basis
for these definitions.

Link: http://lkml.kernel.org/r/1501527386-10736-3-git-send-email-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz 
Acked-by: Michal Hocko 
Cc: Andi Kleen 
Cc: Andrea Arcangeli 
Cc: Aneesh Kumar K.V 
Cc: Anshuman Khandual 
Cc: Arnd Bergmann 
Cc: Davidlohr Bueso 
Cc: Matthew Wilcox 
Cc: Michael Kerrisk 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

UAPI: (Scripted) Disintegrate include/linux

2012-10-13T09:46:48+00:00

Signed-off-by: David Howells 
Acked-by: Arnd Bergmann 
Acked-by: Thomas Gleixner 
Acked-by: Michael Kerrisk 
Acked-by: Paul E. McKenney 
Acked-by: Dave Jones